Generally, when a person boards a vehicle or a boarding device, several safety devices are provided to prevent a passenger from being separated from the vehicle or the boarding device due to impact produced from a collision between vehicles or with other objects.
Among the several safety devices, a representative safety device is a seat belt wherein webbing constituting the seat belt surrounds a lower abdomen and a chest of the passenger to fix stably him/her to a seat thereby preventing the passenger from being separated from the vehicle or the boarding device.
However, recently, various technologies of the seat belt have been developed so that the seat belt is used not only to prevent a passenger from being separated from a vehicle or a boarding device when a vehicle collides with another vehicles or other objects but also to warn to a passenger or protect the passenger in advance even when a vehicle accelerates or rotates rapidly.
That is, various technologies have been developed such that a passenger can be protected in advance from a collision that may be occurred afterwards by figuring-out information of a currently driving vehicle, pulling the webbing constituting a seat belt toward the passenger and notifying the vehicle information to the passenger.